Title: Confronting GRB prompt emission with a model for subphotospheric dissipation

Abstract

The origin of the prompt emission in gamma-ray bursts (GRBs) is still an unsolved problem and several different mechanisms have been suggested. We fit Fermi GRB data with a photospheric emission model which includes dissipation of the jet kinetic energy below the photosphere. The resulting spectra are dominated by Comptonization and contain no significant contribution from synchrotron radiation. In order to fit to the data, we span a physically motivated part of the model's parameter space and create DREAM (Dissipation with Radiative Emission as A table Model), a table model for XSPEC. Here, we show that this model can describe different kinds of GRB spectra, including GRB 090618, representing a typical Band function spectrum, and GRB 100724B, illustrating a double peaked spectrum, previously fitted with a Band+blackbody model, suggesting they originate from a similar scenario. We also suggest that the main difference between these two types of bursts is the optical depth at the dissipation site.

Authors:

Ahlgren, Björn ^[1]; Larsson, Josefin ^[1]; Nymark, Tanja ^[1]; Ryde, Felix ^[1]; Pe'er, Asaf ^[2]

---

+ Show Author Affiliations

1. KTH Royal Inst. of Technology, Stockholm (Sweden). Dept. of Physics
2. Univ. College, Cork (Ireland). Physics Dept.

Publication Date:

Wed Sep 16 00:00:00 EDT 2015

Research Org.:

SLAC National Accelerator Lab., Menlo Park, CA (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1354921

Grant/Contract Number:  

AC02-76SF00515

Resource Type:

Accepted Manuscript

Journal Name:

Monthly Notices of the Royal Astronomical Society: Letters

Additional Journal Information:

Journal Volume: 454; Journal Issue: 1; Journal ID: ISSN 1745-3925

Publisher:

Royal Astronomical Society

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; radiation mechanisms: thermal; gamma-ray burst: general; gamma-ray burst: individual: GRB 090618; gamma-ray burst: individual: GRB 100724B